For example, if you have 22% Haste, it was 1.4sec since the last chance to proc, and you’ve got Windsong, then the chance to proc is 2(ppm) * 1.22(haste) * 1.4(time since last chance) / 60 (sec per min) = 5.693%.

so at 10s proc % = 10%, EACH swing/spell theoretically has 10% chance to proc, which means, its highly likely to have a 100% uptime on this trinket, which of course is wrong, the trinket would be way too OP if so.

My question is, did i misinterpret the blue post formula? What does that resulted proc % really mean?

Basically, enhancement comes out ahead with these trinkets (and the meta) compared to most other melee specs. The only other spec that I think has more baked in attack speed is combat rogues (slice and dice = 40% + haste rating stacking), which is higher than our average (15% from flurry + 10% from AS), but we can also burst higher than that (50% from unleash wind), and flurry's +50% haste rating will also tip the scales in our favor as we start stacking more and more of the stat come next tier.

This is probably part of the reason why the latest balance pass included buffs to several other melee specs + no change for enhancement.

this is extremelly un-probable (with 0,6 rppm, out of 1000 fight of 10min, it should happen only 1-2time that you won't have any proc, and 1.2% chance to have only 1 proc of the whole fight). However if you consider 5min fight you have ~4.3% of chance of not seeing a single proc of the fight, and ~15% chance of not seeing a proc on a 3mn fight. That's intended.

We changed RealPPM to use your true melee haste or spell haste (whichever is higher) to scale the proc rate instead of attack speed or casting speed. The difference is that things that buff your attack speed (such as the raid buff or Slice and Dice) do not increase the frequency of RPPM procs. True haste boosts, such as Bloodlust or haste rating on gear will improve proc rate. We felt this change was necessary to balance proc rates among different specs.

So no, trinket do NOT scale with AS

edit : my bad, for some random reason I always though AS was cast speed and attack speed, I just re-read the tooltip and indeed realPPM trinket should scale with AS, so it should indeed scale.